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# Help with Simultaneous Equation

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1. Hi,

The answer to this is x = 13.

10x + 26(x-3) = 390.

Why? What do I do with the brackets?

Thanks!
2. 10x+26(x-3)=390
10x+26x-70=390 <----- expand the brackets, make sure to multiply 26 by -3
36x = 460 <------ rearrange to get x terms on one side by adding 70
x = 460/36 <------ divide 460 by 36 to get x on its own
x = 12.77777778
x = 13
3. (Original post by ℓove)
10x+26(x-3)=390
10x+26x-70=390 <----- expand the brackets, make sure to multiply 26 by -3
36x = 460 <------ rearrange to get x terms on one side by adding 70
x = 460/36 <------ divide 460 by 36 to get x on its own
x = 12.77777778
x = 13

expand and rearrange for x.
4. (Original post by ℓove)
...
x = 12.77777778
x = 13
If then how does it follow that ?

Does 12.77777778=13??

Just wanted to point that out because it was bothering me...
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Updated: October 11, 2016
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